Handle bar extension



FIG. 1 is a perspective view showing the top, left side and front of a handle bar extension which form my new design, the broken lines of a handle bar being for illustrative purposes only and forming no part of the claimed design;

FIG. 2. is a top plan view thereof, this view and the opposite bottom plan view being mirror images;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof; and,

FIG. 6 is a right side elevational view thereof. 

The ornamental design for a handle bar extension, as shown and described. 